Historic phone call, then optimism for US, Iran

President Barack Obama gestures while making a statement regarding the budget fight in Congress and foreign policy challenges, Friday, Sept. 27, 2013, in the James Brady Press Briefing Room of the White House in Washington. The president said the debt ceiling breach far worse than a government shutdown and would effectively shutter economy. (AP Photo/ Evan Vucci)
— AP

President Barack Obama gestures while making a statement regarding the budget fight in Congress and foreign policy challenges, Friday, Sept. 27, 2013, in the James Brady Press Briefing Room of the White House in Washington. The president said the debt ceiling breach far worse than a government shutdown and would effectively shutter economy. (AP Photo/ Evan Vucci)
/ AP

Iranian President Hassan Rouhani takes his chair before a news conference at the Millennium Hotel in midtown Manhattan, Friday, Sept. 27, 2013, in New York. (AP Photo/John Minchillo)
/ AP

President Barack Obama gestures while making a statement regarding the budget fight in Congress and foreign policy challenges, Friday, Sept. 27, 2013, in the James Brady Press Briefing Room of the White House in Washington. The president said the debt ceiling breach far worse than a government shutdown and would effectively shutter economy. (AP Photo/ Evan Vucci)— AP

President Barack Obama gestures while making a statement regarding the budget fight in Congress and foreign policy challenges, Friday, Sept. 27, 2013, in the James Brady Press Briefing Room of the White House in Washington. The president said the debt ceiling breach far worse than a government shutdown and would effectively shutter economy. (AP Photo/ Evan Vucci)
/ AP

WASHINGTON 
The Iranian president, his visit to the U.S. nearing its end, makes contact with the White House. As his car inches through New York's snarled traffic, he hears Barack Obama's voice on the phone as the U.S. president sits at his desk in the Oval Office.

Fifteen minutes later, the two men say goodbye in each other's language.

And with that, a generation-long rift between the U.S. and Iran is that much closer to being bridged.

Iranians awoke Saturday to learn that their president, Hassan Rouhani, had spoken directly to Obama, breaking through a barrier that had left American and Iranian presidents divorced from such contact for 34 years. The two presidents pledged to resolve concerns about Iran's nuclear ambitions, which have isolated Iranians from the global community and led to crippling economic sanctions.

Upon his arrival home to Tehran, the Iranian president was met by both cheering supporters and opposition hardliners who tried to block his motorcade.

Several dozen protesters shouted "Death to America" and at least one reportedly hurled a shoe, a gesture of contempt. Supporters, meanwhile, greeted Rouhani with cheers and placards praising his peace efforts.

The appetite for serious talks having been tested at a presidential level, the focus turns to negotiations among foreign ministers and other officials from the five permanent members of the U.N. Security Council plus Germany, who together will chart a path forward, a senior Obama administration official said. The group wants Iran to present a more detailed proposal before or at the next round of negotiations, scheduled in Geneva on Oct. 15-16, another U.S. official said.

Rouhani's aides initially reached out to arrange the call, said officials, who weren't authorized to comment by name and demanded anonymity. But it was Obama who signaled days earlier he was willing to meet with his Iranian counterpart.

By the end of the call, Obama was suggesting that a breakthrough on the nuclear issue could portend even deeper ties between the U.S. and Iran, a notion that would have seemed unfathomable in recent years, when Rouhani's predecessor was describing America in satanic terms.

The telephone call capped a week of seismic shifts in the relationship while Rouhani was in the U.S. for an annual U.N. meeting. Obama had left open the possibility of an exchange with Rouhani, but the Iranian later said the timing wasn't right.

But hours before the phone call, at a news conference in New York, Rouhani linked the U.S. and Iran as "great nations." And the night before, U.S. and European diplomats were hailing a "very significant shift" in Iran's attitude and tone in the first talks on the nuclear standoff since April.

"While there will surely be important obstacles to moving forward, and success is by no means guaranteed, I believe we can reach a comprehensive solution," Obama told reporters Friday at the White House.

The shift in tone aside, there was immediate skepticism that Iran was cynically seeking to procure relief from economic sanctions but would not take concrete action to assuage global concerns that it is seeking to build nuclear weapons.